For the validation of advanced two-fluid CFD models at boiling water reactor (BWR) conditions, it is necessary to have good experimental data challenging for the code by reflecting relevant flow phenomena. The present experimental study aims to provide detailed film thickness distributions in a BWR-like subchannel geometry, including spacer grids and heat transfer. This is achieved using chloroform as a working fluid, indirectly heated by hot water channels simulating BWR fuel rods. X-ray equipment was used to produce tomographic 3D-data of time-averaged attenuation coefficients which essentially represent the liquid holdup. The conversion to film thickness was done by integrating the attenuation coefficient along lines perpendicular to the rod wall and using an effective chloroform attenuation coefficient determined by numerical simulation of the experimental setup, including X-ray sensor behavior. The simulation method was validated by using two different sensors types. Measurements were performed over the whole cross-section of the channel and an axial length of 11 cm. The experiments cover a range of liquid flow rates in the pre- and post-dryout regime.

为了在沸水反应堆（BWR）条件下验证先进的双流体CFD模型，有必要通过反映相关的流动现象来获得具有挑战性的良好实验数据。本实验研究旨在提供BWR状子通道几何形状的详细膜厚分布，包括间隔栅和热传递。这是通过使用氯仿作为工作流体，通过模拟BWR燃料棒的热水通道间接加热来实现的。使用X射线设备生成时间平均衰减系数的X线断层摄影3D数据，该系数基本上代表了液体滞留率。通过将沿垂直于棒壁的线的衰减系数积分并使用有效的氯仿衰减系数（通过X射线传感器行为对实验装置的数值模拟确定），可以完成向膜厚的转换。通过使用两种不同的传感器类型验证了仿真方法。在通道的整个横截面和11 cm的轴向长度上进行测量。实验涵盖了干燥前后的液体流速范围。